Here is what shows up in the console after the error. The plugin seems to be working properly, but I noticed that someone else had posted on the comments that they too had this problem.

java.lang.NullPointerException
com.nerdswbnerds.easywarp.objects.Warp.toString(Warp.java:33) ~[?:?]
com.nerdswbnerds.easywarp.managers.FileManager.saveWarps(FileManager.java:46) ~[?:?]
com.nerdswbnerds.easywarp.EasyWarp.onDisable(EasyWarp.java:31) ~[?:?]
org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:252) ~[craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
org.bukkit.plugin.java.JavaPluginLoader.disablePlugin(JavaPluginLoader.java:374) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
org.bukkit.plugin.SimplePluginManager.disablePlugin(SimplePluginManager.java:408) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:401) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
org.bukkit.craftbukkit.v1_7_R1.CraftServer.disablePlugins(CraftServer.java:390) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
net.minecraft.server.v1_7_R1.MinecraftServer.stop(MinecraftServer.java:375) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:488) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]